Center up some shots in a standing position like when you're about to launch and then center some shots on your belly, it does make a difference at least in my case. I do use a "paper asshole" (clear type thats colored with a red marking pen making it translucent.). I have to look low in the standing position, but other than that it's centered. I prefer to not have a fixed site as I make a lot of fun jumps with camera and it can get funnelishis at times. I'd like to see things from your point of view, but I can't get my head that far up my ass.